In the field of frequency bandwidth reduction systems wherein the bandwidth used in radio communication is reduced so that an increased number of channels are available in the airways, there is no known prior frequency modulation system for reducing the frequency bandwidth to less than 15 kilohertz. And, all prior systems that achieve reduction to less than 10 kilohertz reduce the bandwidth by restricting the audio frequency range. This is accomplished by arbitrarily cutting off audio frequencies above and below a narrow audio range. Such an audio frequency range might be, for example, from three kilohertz to 300 hertz. As a result, considerable distortion is encountered and, therefore, the type and amount of information which can be transmitted is restricted.